How long has the cat known you? It was exactly the same with my cats, but they gradually let me touch their bellies and paws more and more. A declawed cat feels defenseless, so if they don't yet fully trust you, they'll be all the more scared of letting you get near those places, and will use their teeth more. I would say time is key.

__________________The Royal von Meouw Dynasty: His Royal Highness the late Prince von Meouw,
Her Royal Highness Princess Gatita von Meouw, Nikita Duchess of Meouw and
His Highness Cuchi-Cuchi, next in line for the throne of Prince von Meouw.

Cleo was the same way, but she didn't want to be touched ANYWHERE. She's not declawed, but she was tormented by a little brat who grabbed her by her legs and feet. Four years later, she still doesn't like her legs or feet touched, but I can pet her everywhere else.

tuna, something you might try to get your cat to enjoy his feet touched is put just a little smear of butter on top of his feet. You could also use some chicken fat or tuna juice if he likes those things. He will come to enjoy licking it off. Eventually he should come to look forward to you touching the top of his paws as he'll anticipate this little treat. Don't rush it, and when he's dong well with you touching the top of his paws, then touch more of his legs, but only do so much that he's tolerating and enjoying it.

Also the old trick of starting with something new they don't enjoy when they're sleepy...

__________________The Royal von Meouw Dynasty: His Royal Highness the late Prince von Meouw,
Her Royal Highness Princess Gatita von Meouw, Nikita Duchess of Meouw and
His Highness Cuchi-Cuchi, next in line for the throne of Prince von Meouw.